" if( uIsoAmt > 0.0 ){\n"
" float height = fract( aCo.y * 0.1 );\n"
" float lg = 2.0*length(vec2(dFdx(height), dFdy(height)));\n"
" if( uIsoAmt > 0.0 ){\n"
" float height = fract( aCo.y * 0.1 );\n"
" float lg = 2.0*length(vec2(dFdx(height), dFdy(height)));\n"